Fractions- Multiplication of Fractions.ppt

How to multiply fractions

1. Vulgar Fractions
IGCSE MATHEMATICS
0580
Digitized Notes
Multiplication of Fractions

2. Times You Would Multiply a Fraction
Times a Fraction
• Your family eats 1/8 of 1/2 of
a left over wedding cake.
1/8 of 1/2 or 1/8 x 1/2

3. Times You Would Multiply a Fraction
Times a Fraction
•Jose had already read 1/2 of his
novel. Today he read 1/12 of the
1/2 left. How much of the book
has he read?
1/12 of 1/2 or 1/12 x 1/2

4. Multiplying Fractions
Conceptual Understanding
•When you multiply two fractions
that are between 0 and 1 the
product is smaller than both
fractions.
½ x ¾ = 3/8
Look at the diagram on the
next slide to understand why.

5. Multiplying Fractions
Conceptual Understanding
½ x ¾ = 3/8
¼¼¼¼
1/81/81/8

6. How to Find a Fraction of a
Fraction
• The first thing to remember is “of”
means multiply in mathematics.
of=x

7. How to Find a Fraction of a
Fraction
•
Step 1 - When you see a fraction
problem you know when you read
“of” in the problem you multiply.
ofx
1
2
4
9

8. How to Find a Fraction of a Fraction
•
Step 2 – Multiply your
numerators straight across.
x 4
9
1
2
=
4

9. How to Find a Fraction of a Fraction
•
Step 3 – Then multiply your
denominators straight across.
x 4
9
1
2
=
4
18

10. How to Find the Fraction of a
Fraction
•
Step 4 – Simplify your answer.
In this case we reduce.
x 4
9
1
2
=
4
18
÷
÷
2
2
=
2
9

11. Multiply and Simplify
9
5
1
6
=
9
3010
3
x
÷
÷
3
3
=

12. Multiply and Simplify
3
4
8
9
=
24
36 3
2
x
÷
÷
12
12
=

13. Multiply and Simplify
4
3
7
2
=
28
66)28
4
x
24
4
4
4
6
÷
÷
2
2
=
2
3
4

14. Multiply and Simplify
9
2
3
4
=
27
88)27
3
x
24
3
3
8

15. Multiply and Simplify
8
2
7
3
=
56
66)56
9
x
54
2
2
6
9
2
6
÷2
2
=9
1
3÷

16. Multiply and Simplify
3
4
4
2
=
12
88)12
1
x
8
4
4
8
1
4
8
÷4
4
=1
1
2÷